that either they themselves or people they know want to upgrade to iOS 8 but haven’t yet or can’t because the OTA software update won’t fit on their devices.
Jonathan Hoover puts it well:
iOS 8 OTA update requires about 5GB of free space on the device. Most people, especially those who wouldn’t update until they get the badge on the settings app, don’t have 5GB free on their iPhone. They have no idea they can plug their iPhone into their computer and iTunes will update it. They don’t know they can free up space by downloading their pictures and videos to their computer.
iPhone makes it so easy for casual users to take gigabytes of photos and videos but nearly impossible for those users to know what to do with them.
This is a serious problem for Apple, because all those 16 GB devices (let alone the 8 GB ones) aren’t going to suddenly gain more free storage space on their own. A lot of these devices might never get updated to iOS 8, but would if the OTA software worked. Unless they can rejigger the OTA software update to require less free space, iOS 8’s adoption rate might lag permanently.
Apple need to either start selling larger storage-capacity devices and stop selling 8 and 16gb versions and/or they need to reduce the footprint of the over the air annual iOS update – either way, they need to address this matter soon as it is affecting their adoption growth which they proudly like to talk about at their keynotes.